Electrostatic image development apparatus

ABSTRACT

Apparatus for developing latent electrostatic images in which a uniform concentration of toner powder is maintained throughout the developer system. Toner powder is uniformly dispensed to the developer mixture which mixture is magnetically attracted to the surface of a moving cylindrical applicator and transported to contact the latent electrostatic images to be developed. The images to be developed are transported in the axial direction relative to the moving cylindrical applicator and the developer material on the applicator is continuously agitated in both the axial and transverse directions across the development zone.

United States Patent Rueckwald 1 1 Mar. 14, 1972 154] ELECTROSTATIC IMAGE DEVELOPMENT APPARATUS [72] Inventor: Ronald F. Rueekwald, Rochester, NY. [73] Assignee: Xerox Corporation, Rochester, NY.

[22] Filed: May 12, 1969 [21] App1.No.: 823,878

Related US. Application Data [63] Continuation-impart of Ser. No. 733,879, June 3,

1963, Pat. No. 3,538,887.

[52] [1.5. CI ..118/637, I 17/175 [51] Int. Cl. ..G03g 13/08 [58] FieldolSearch ..118/623,637,312;117/175; 96/14 [56] References Cited UNITED STATES PATENTS 1,801,572 4/1931 Salerno ..118/312 X 2,786,441 3/1957 Young ..118/637 2,910,963 11/1959 Herman ..118/623 2,940,422 6/ 1960 Dott 3,133,834 5/1964 Sowiak 3,140,199 7/ I 964 York 3,190,264 6/1965 Hunt 3,219,014 11/1965 Mott et a1... 3,333,572 8/1967 Olden ..1 18/637 Primary Examiner-Mervin Stein Attorney-James J. Ralabate, John E. Beck and Benjamin B. Sklar 1 1 ABSTRACT Apparatus for developing latent electrostatic images in which a uniform concentration of toner powder is maintained throughout the developer system. Toner powder is uniformly dispensed to the developer mixture which mixture is magnetically attracted to the surface of a moving cylindrical applicator and transported to contact the latent electrostatic images to be developed. The images to be developed are transported in the axial direction relative to the moving cylindrical applicator and the developer material on the applicator is continuously agitated in both the axial and transverse directions across the development zone.

6 Claims, 7 Drawing Figures Patented March 14, 1972 3,648,657

4 Sheets-Sheet 1 INVENTOR RONALD F. RUECKWALD ATTORNEY Patented March 14, 1972 3,648,657

4 Sheets-Sheet 2:

Patented March 14, 1972 4 Sheets-Sheet I5 Patented March 14, 1972 4 Sheets-Sheet 4 ELECTROSTATIC IMAGE DEVELOPMENT APPARATUS This application is a continuation-in-part of copending application Ser. No. 733,879, filed June 3, I968, now US. Pat. No. 3,538,887, issued Nov. 10, 1970.

BACKGROUND OF THE INVENTION This invention relates generally to apparatus for developing latent electrostatic images and more particularly for apparatus for applying developer powder or toner to electrostatically charged latent images on a support member.

In the art of electrographic recording, a pattern of electrostatic charges is placed on a suitable dielectric support material in a configuration corresponding to the desired information record. This pattern of electrostatic charges may be applied directly to the recording surface by an electrographic recording stylus, an electrode array, or any of the other known electrographic recording means. Subsequently, the charge pattern is developed or toned by a suitable toner material which may comprise a pigmented thermoplastic resin. Subsequent to the development process, the toner material on the dielectric support member is fused to the support to form a permanent copy of the information.

The process of electrographic recording in some aspects is similar to the now well known xerographic process. That is, in both processes patterns of electrostatic charges are created which correspond to the desired information record. In the process of xerography, this is accomplished by blanket charging of a photoconductive insulator, and then selectively discharging portions thereof by exposure to light, generally through a suitable optical system. However, the process of electrographic recording differs from the process of xerography in that the charge pattern in electrographic recording is created without the use of photosensitive materials. That is, the process of xerography requires the use of a suitable photoconductor, whereas the process of electrographic recording does not.

An apparatus which utilizes the electrographic recording process is that which has been described in copending application, Ser. No. 758,932, filed Sept. ll, I968, in the names of Halbert M. Harris et al., now U.S. Pat. No. 3,588,335, and assigned to the same assignee as the instant invention. As described therein, electrographic recording styli are utilized to apply a charge pattern in image configuration to a suitable dielectric recording medium. As the styli are traversed relative to the support medium, one suitable medium being for example ordinary cut sheet paper stock, a suitably high voltage or potential is applied across the dielectric recording medium to produce a latent residual charge pattern of graphic information. In the particular apparatus referred to above, an electrical signal is generated as a result of the scanning of a document at another location by measuring reflected light levels of the information thereon. This electrical signal is then utilized to control the voltage or potential applied to the styli at any point in time representative of the reflectivity of a dot or small portion of the scanned information. Thus, for example, if an applicably high voltage is applied to the styli by an electronic drive circuit, a residual voltage proportionate to the applied voltage level will remain on the surface of the dielectric, the residual voltage, however, decaying with time and as a function of ambient conditions.

In comparison to the residual voltages retained on a photoconductor in the xerographic process, the residual voltages retained on the dielectric support member in the electrographic recording process are generally of substantially lesser magnitudes. Because of the lesser magnitude of retained residual voltages on the surface of the dielectric, the development of the electrographically produced latent images have therefore presented certain problems which have not heretofore been a consideration in the development of latent electrostatic images produced by xerographic processes.

Accordingly, the development of electrographically produced latent electrostatic images by known xerographic developing apparatus has not produced images to a degree of uniformity and resolution required according to modern day copy quality standards. In contrast, however, the same xerographic developing apparatus has been quite effective for producing copies of the highest possible quality from xerographically produced images. Although development of electrographically produced latent electrostatic images by known xerographie developing apparatus has not produced images to a degree of uniformity and resolution required, apparatus which has been found effective for the development of electrographically produced latent electrostatic images has nevertheless been found effective in the development of xerographically produced latent electrostatic images.

In the development process, the toner particles, which are many times smaller than the carrier material, adhere to and coat the surface of the carrier material due to triboelectric attraction therebetween. During development, as the tonercoated carrier material is applied to an electrostatic image of a polarity opposite to the charge on the toner, toner particles are pulled away from the carrier material by the latent electrostatic image and deposited on the latent electrostatic image bearing support material to fonn a developed toner powder image.

As the toner powder in the developer mixture is depleted during the development of the latent image on the support surface, more toner powder must be added to maintain a desirable level of copy density. in the event that too much toner powder is added to the developer mixture, heavy deposits of toner in the image areas in combination with an undesirable deposit of toner in the nonimage or background areas results in producing prints of poor contrast with blotchy images or poor resolution.

Heretofore, various attempts to maintain a uniform mixture of toner powder in the developer mix have generally been directed to the addition of toner powder into a static or substantially stationary quantity of developer material. While such systems are somewhat satisfactory, they have certain obvious shortcomings. For example, when toner powder is added to a static or substantially stationary quantity of developer material, the intermixing of the toner powder with the carrier material becomes very difficult resulting in a deficient triboelectric relationship between the toner powder and carrier. In addition, if the images being reproduced have large solid areas in one portion, then the developer material tends to become depleted of toner powder in this localized area. Furthermore, the time delay required to intermix the additional toner powder into the developer material results in a number of initial prints of poor quality.

It is therefore highly desirable to have a developer system in which the addition of toner powder into the developer mixture is continually metered and uniformly dispensed into a moving or dynamic developer mixture such that an intermixing of the developer material and the toner powder is achieved throughout the developer system resulting in a uniform high quality application of developer material to the latent electrostatic image.

SUMMARY OF TI-[E INVENTION Accordingly, it is an object of the present invention to provide development apparatus for rendering latent electrostatic images visible.

It is another object of the present invention to provide improved latent electrostatic image development apparatus for producing copies having a high degree of uniformity and resolution.

It is another object of the present invention to provide improved electrostatic image development by controlling the quantity of toner powder added to a developer mixture.

It is still another object of the present invention to provide improved electrostatic image development by maintaining a high degree of intermixing between carrier particles and toner powder.

It is yet another object of the present invention to provide apparatus for effectively rendering latent electrostatic images visible from both electrographically and xerographically formed images.

It is still a further object of the present invention to provide apparatus for developing electrographically produced latent electrostatic images yielding copies having a high degree of uniformity and resolution from relatively low voltage variable density residual charge patterns.

It is still another object of the present invention to provide improved electrostatic image development by maintaining a highly intermixed quantity of developer material throughout the developer system.

It is yet a further object of the present invention to provide improved latent electrostatic image development apparatus which maintains a uniform concentration of electroscopic toner powder across the development zone.

It is yet a further object of the present invention to provide improved development apparatus which maintains a continuous intermixing of the developer material in the toner powder throughout the development zone.

It is yet a further object of the present invention to provide latent electrostatic image developing apparatus which maintains a continuous intermixing between toner powder particles and carrier particles.

These and other objects of the present invention are attained by means of a housing member adapted for storing a quantity of magnetically attractable developer material comprising magnetic carrier particles and triboelectrically charged toner particles, a generally cylindrical applicator member rotatably journaled in said housing member for transporting a quantity of developer material from said housing member into transfer relation with a support member having latent electro static images thereon, magnetic means within said applicator member for generating a magnetic field and attracting developer material from the housing member onto the applicator member, the magnetic means having lines of force extending in both the axial and circumferential directions relative to the cylindrical applicator member to produce a movement of the developer material in both the axial and circumferential directions on the applicator member, and means for supporting and advancing a support member having electrostatically charged latent images thereon over the applicator member and the developer material in the axial direction relative to the rotation ofthe applicator member.

Other objects of the invention will become readily apparent to those skilled in the art in view of the following detailed disclosure and description thereof, especially when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an automatic electrographic facsimile transceiver apparatus in which the arrangement as contemplated by the present invention is particularly adapted for use.

FIG. 2 is a perspective schematical illustration of the various components of the transceiver apparatus of FIG. 1.

FIG. 3 is a partial plan view showing the dispensing apparatus as contemplated by the present invention.

FIG. 4 is a sectional view showing one embodiment of developer apparatus as contemplated by the present invention.

FIG. 5 is a sectional view showing a second embodiment of developer apparatus as contemplated by the present invention.

FIG. 6 is a plan view partly broken away of the applicator and magnet arrangement of FIG. 4.

FIG. 7 is a plan view partly broken away showing the applicator of FIG. 5 with an alternative magnet arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. I of the drawings, there is illustrated a facsimile transceiver apparatus in which the arrangement as contemplated by the present invention is particularly adapted for use. While the invention as described herein may be referred to as particularly adapted for use in such transceiver apparatus, it should be understood and it will be readily appreciated by those skilled in the art that the arrangement as contemplated by the present invention may be readily adapted for use in connection with both electrographic and xerographic recording processes.

As may be seen from FIG. 2, an automatic electrographic facsimile transceiver apparatus includes an inner platen support member 500 having a convex semicylindrical surface extending axially therealong and an outer platen support member 500 having a concave semicylindrical surface extending axially therealong which combine to form a curvilinear passageway through which a record medium or sheet of electrographic recording material is advanced. A rotatable optical scanner and electrographic recorder turret apparatus 700 is positioned adjacent the passageway to functionally form a scanning-recording station axially positioned along the two semicylindrical surfaces over which the electrographic recording material passes.

When it is desired to transmit the graphic information on the record medium, the sheet is advanced to the scanning station 700 whereat electrical signals representative of the graphic information carried thereon are generated as the optical scanner traverses the graphic information on the sheet. When it is desired to receive information from a remote location, the recorder portion of the turret selectively produces electrostatic charge patterns on the electrographic paper record medium, as it is forwarded within the passageway at the recording or scanning station, in response to electrical signals received by the recorder and representative of the graphic information which is desired to be displayed on the record medi- After a latent electrostatic image has been formed on the record medium by the selective deposition of electrostatic charge patterns thereon, the charge patterns representative of the graphic information are rendered visible by means of the developing apparatus generally designated 400, which uniformly deposits a quantity of toner powder onto the charged surface of the latent electrostatic image bearing record medium. After the latent image is rendered visible, the toner powder image on the surface of the record medium is permanently affixed thereto to provide a facsimile copy of the graphic information thereon.

For purposes of the present disclosure, reference will be made primarily to use of the facsimile transceiver apparatus in the receive mode of operation, although it is to be understood that the transceiver unit is designed to function both as a transmitter and a receiver. When the automatic electrographic facsimile transceiver apparatus 100 is operated in the receive mode, sheets of electrographic recording material upon which the graphic information is to be recorded are placed into the machine on a record material tray 102 located at the front of the machine and directly beneath a second copy support tray 10] utilized when the transceiver apparatus is operated in the transmit mode. The record sheets 105 are advanced from the tray 102 by means of an automatic sheet feeder and are transported into the passageway defined between inner platen assembly 500 and outer platen assembly 550 by means of a sheet transport generally designated 350. The electrographic recording sheets are forwarded into position within the passageway defined between the inner and outer platen assemblies 500 and 550, respectively, and then advanced to the scanner-receiver area by a paper drive mechanism generally designated 600. At the scan-receive turret 700, and upon receipt of suitable electrical control pulses, the paper drive 600 is removed from engagement with the electrographic recording sheet and a stepping drive mechanism 650 engaged therewith to advanced the copy sheet at a controlled speed past the scanner-receiver 700.

Information is recorded upon the electrographic record sheet 105 by means of an electrographic recording stylus supported on the rotating turret assembly 700 for rotation therewith to selectively charge an increment of the electrographic recording material, in response to electrical control signals, as the recording material is advanced thereover. The information desired to be recorded on the copy sheet 105 is received by the transceiver apparatus, decoded through appropriate electrical circuitry and utilized to energize the electrographic recording stylus in the turret assembly 700. In response to these electrical control pulses, the record or copy sheet 105 is electrographically charged in image patterns corresponding to the information coupled into the transceiver apparatus. Upon completion of the recording process the copy sheet 105 is advanced by the stepping drive assembly 650 over the developer unit 400 whereat the latent electrostatic charge pattern on the sheet is rendered visible by application of the electroscopic toner powder particles which adhere to the record sheet in the charged areas. After the latent electrostatic image on the record sheet has been rendered visible by electroscopic toner powder the copy sheet is further advanced along the curvilinear path to a fusing apparatus generally designated 800 at which point the electroscopic toner powder particles are fused to the copy sheet to create a permanent facsimile copy of the graphic information displayed on the support material. For a more complete description of the fusing apparatus generally designated 800, reference may be had to copending application Ser. No. 733,468 filed May 31, 1968 in the name of Charles L. Huber, now U.S. Pat. No. 3,535,492, and assigned to the same assignee as the instant invention. After the toner powder image has been permanently affixed to the record sheet, the sheet 105 is advanced to a sheet transport 900 whereat the completed facsimile copy is forwarded out of the machine and into the copy receive tray 103 located at the front portion of the transceiver.

As may be seen from FIG. 2, the developing unit 400 is appropriately positioned adjacent the passing electrographic support material 105 in a manner such that the developer material contained thereon contacts the support material for the development of the latent electrostatic image by the application ofelectroscopic toner powder.

The developing unit 400 includes a rotatable magnetically permeable drum member 420 which is supported within the developer unit housing on shaft 430 for rotation about a plurality of permanent magnets 450. As may be seen from FIGS. 6 and 7, drum member 420 includes a pair of end plates 42] and 422 axially spaced from each other which combine to form the hollow cylindrical applicator member 420. Drum member 420 is rotatably supported in relation to shaft 430 by means of bearings 423 and 424 which are respectively connected to end plates 421 and 422.

The magnets 450 are supported internally of the applicator member 420 and are positioned closely adjacent to the path of drum travel. A disc member 432 is supported on shaft 430 by means of a collar member 431 which is secured to disc member 432 and shaft 430 by suitable connecting means. An annular ring member 433 is connected about the outer periphery of disc member 432 and has connected thereto a plurality of permanent magnets 4S0.

Drum member 420 with magnet members 450 supported internally therein is supported for rotation within the developer housing which comprises a bottom plate 449 and front and rear frame plates 447 and 448 which are connected to bottom plate 449. As may be seen from FIGS. 4 and 5, a sump 444 at the lower portion of the developer housing contains a quantity of developer material to be used in the development process which includes a quantity of magnetic carrier particles, e.g., iron filings and a quantity of toner powder which adheres to the magnetic carrier particles.

In the embodiment of developer apparatus as illustrated in FIGS. 4 and 6, the magnets 450 extend only throughout a portion of the total distance of drum travel about annular ring member 433. This arrangement provides therefore an area along the path of drum travel in which no significant magnetic field is present. In the arrangement illustrated in FIGS. 4 and 6, drum member 420 may be driven in the clockwise direction as viewed in FIG. 4 by means of a suitable drive arrangement such as drive sprocket 425 connected to bearing member 424. In this manner through a suitable drive arrangement, drum member 420 may be rotated about shaft 430 while shaft 430 with disc member 432 and magnet members 450 supported thereon is held stationary against rotation. As drum member 420 is thus rotated, developer material from sump 444 will be attracted to the surface of drum member 420 by means of the magnetic field formed by magnet members 450. As drum member 420 continues to rotate, developer material will continue to be attracted to drum member 420 by means of the magnetic field generated by the successively spaced magnet members 450. As the developer material is lifted from the sump 444 upwardly about the path of rotation of drum member 420 a doctor blade 445 supported inwardly of base plate 449 engages the brush of developer material adhering to drum member 420 causing the brush passing doctor blade 445 to have a uniform thickness of developer material on drum 420. With outer platen assembly 550 in the closed position as shown in FIG. 4, a copy sheet having the latent electrostatic charge patterns thereon which is to be developed is sup ported between outer platen member 550 and the moving brush of developer material supported on drum member 4211. Copy sheet 105 is advanced over drum member 420 and the brush of developer material by means of the drive mechanism 600 and 650 in a direction along the axis of shaft 430. Thus the movement of the magnetic brush with the developer parti cles supported on drum 420 moves transversely to the direction of movement of the copy sheet 105 having the latent electrostatic image thereon which is to be developed. As the magnetically attractable developer particles reach the area about the path of travel at which there is a spacing of the mag net members 450, the magnetic field attracting the developer material to the surface of drum 420 is no longer present thus permitting the developer material to fall from the drum surface onto the conveyor 321 of toner dispenser 300.

The toner powder dispenser 300 includes a hopper or container 310 for holding a quantity of electroscopic toner powder to be dispensed into the developer mixture to replenish the toner powder used to develop the latent electrostatic images on the electrographic support material 105, and a conveying apparatus 320 for removing a quantity of toner powder from the container 310 and forwarding the powder through a toner powder replenishing zone whereat the developer mixture utilized in developing the latent electrostatic images falls from the developing drum 420 onto the toner powder laden conveyor belt 321 to be intermixed therewith and thereafter conveyed to sump 444 whereat the toner-replenished developer material is recirculated by the developing drum 420. The dispensing apparatus 300 is supported within the developer unit 400 between front and rear frame plates 447 and 448, respectively, by means of a pair of brackets 323 secured to the bottom plate 449 of the developer unit and the frame 322 ofthe conveying apparatus 320.

Dispensing of the toner powder into the developer mixture is regulated by the adjustable positioning of the hopper 310 relative to the conveyor belt 321 of the conveying apparatus 320. Hopper 310 comprises a hollow rectangular housing open at the top for addition of toner powder and at the bottom for the dispensing of toner powder in cooperation with conveyor belt 321 into the developer mixture. The hopper is appropriately secured, as by welding, to pivot shaft 324 pivotable in a pair of brackets 325 secured to the frame of conveyor apparatus 320. A spring 332, secured at one end to hopper 310 and at its other end to frame plate 446 of the developer unit, biases the hopper in a clockwise direction as seen in FIGS. 4 and 5 against a threaded adjustable stop 333 whereby the spacing between the bottom of hopper 310 and the top run of conveyor belt 321 can be adjusted by rotating the hopper on pivot shaft 324 by means of turning the knob of adjustable stop 333. The positioning of hopper 310 relative to conveyor belt 321 defines an aperture through which toner powder passes on the conveyor belt, the quantity of powder dispensed being determined by the spacing between these elements for a given constant linear velocity of the conveyor belt.

The conveying apparatus 320 includes a frame 322, supported from bottom frame plate 449 of the developer unit by means of the pair of brackets 323, positioned adjacent developer drum 420 such that developer material falling therefrom will fall onto the toner powder laden conveyor belt as it emerges from beneath hopper 310. The belt is supported about idler roller 326 and drive roller 327 each roller being rotatably supported in conveyor frame 322. Idler roller 326 is adjustably supported in frame 322 by means of a tension bracket 328 to maintain the conveyor belt 321 in a predetermined stressed configuration. The drive roller 327 is rotatably supported in frame 322 and driven by means of an electric motor MOT-l appropriately supported from the developer unit 400 and connected to drive roller 327 by means of a sleeve coupling 35].

As developing drum 420 rotates within the developer housing the developer mixture which passes out of the magnetic field from magnets 450 is no longer held on developing drum 420 and, therefore, falls from the drum surface onto the toner powder laden conveyor belt 321 positioned adjacent thereto. A pair of baffles 329 are supported from each side of conveyor frame 322 and extend perpendicular to the surface of conveyor belt 321 to constrain the developer mixture onto the conveyor belt to ensure mixing of the toner powder with the toner powder depleted developer mixture. After the developer mixture has been replenished with toner powder, the mixture is conveyed to developer sump 444 from where the replenished developer mixture is recycled for image development.

In the embodiment of developer apparatus as illustrated in FIG. 5, the magnets 450 are arranged to extend throughout the total distance of drum travel. In this arrangement, a scraper blade 45! is supported between frame plates 447 and 448 above conveyor belt 321. Scraper blade 451 is positioned in close proximity to the surface of cylindrical applicator member 420 to engage and remove the developer material from applicator member 420. Scraper blade 451 is positioned between frame plates 447 and 448 at an inclination to permit the developer material removed from applicator member 420 to fall onto conveyor belt 321. In the embodiment as illustrated in FIG. 5, disc member 432 and magnet members 450 supported thereon may be held stationary against rotation as in the embodiment described in connection with FIG. 4. However, in the embodiment as illustrated in FIG. 5, disc member 432 with magnets 450 supported thereon is preferably rotated in a direction opposite to the direction of rotation of drum member 420. To this end, a suitable drive arrangement such as that illustrated in FIG. 7 is provided. As shown in FIG. 7, drum member 420 may be driven in a first direction of rotation by means of a suitable drive arrangement such as drive sprocket 425 operatively connected in a driving arrangement from a source of motive power. In a similar manner, shaft 430 may be driven in a second direction of rotation, for example a direction opposite to the direction of rotation in which drum member 420 is driven, by means of a suitable drive arrangement such as drive sprocket 426 operatively connected to a source of motive power. From this arrangement, drum member 420 may be driven in the clockwise direction as viewed in FIG. whereas magnet members 450 may be rotated in a counterclockwise direction as viewed in FIG. 5.

In the development apparatus as illustrated in FIGS. 4, 5, and 6, magnet members 450 have been illustrated as horseshoe shaped magnets having the poles positioned closely adjacent the inner surface of cylindrical applicator member 420. It will be observed from FIG. 6, that magnet members 450 are arranged on disc member 432 in an arrangement having an alternating polarity. That is, the poles of the individual magnet members 450 are arranged with the poles thereof in an alternating north-south arrangement about the periphery of annular member 433. It should be also noted that the individual magnet members 450 are positioned on annular member 433 at an inclination to the axis of shaft 430 about which they are rotated. In the arrangement shown in FIG. 6, magnet members 450 are inclined at an angle of approximately 45 relative to the axis of shaft 430.

An alternative to the horseshoe shaped magnets 450 as illustrated in FIGS. 4-6 has been illustrated in FIG. 7. As may be seen from FIG. 7, a plurality of bar magnets 450 are supported about the periphery of annular member 433. As may be seen from FIG. 7, bar magnets 450' are similarly arranged about annular member 433 in an alternating polarity. That is, magnet members 450' are spaced thereabout with the poles thereof in an alternating north-south arrangement. In the arrangement shown in FIG. 7, two columns of magnet members 450 have been illustrated as extending about the periphery of annular member 433. However, it will be readily understood by those skilled in the art that additional magnet members 450' may be provided, depending upon the size of the individual magnet members and the respective axial dimensions of annular member 433 and applicator member 420.

In the embodiments of both FIGS. 6 and 7, it will be appreciated by those skilled in the art that the lines of force between the respective poles of the individual magnet members 450 and 450 extend not only in the circumferential direction between alternating poles about applicator member 420 but also extend between opposite poles in the axial direction along applicator member 420. However, because of the specific arrangement of the magnet members 450 and 450', the lines of force extending in the axial direction relative to shaft 430 are inclined from the axis of shaft 430 at an angle of approximately 45 relative thereto.

The developer material is supported on applicator member 420 by magnets 450 and 450 in a manner generally resembling the bristles of a brush. This is the result of the tendency of the magnetic particles to align with the lines of force extending between opposite poles of the individual magnet members 450 and 450'. Thus, the disposition of the developer material supported on applicator member 420 is largely a function of the directional disposition of the lines of force between opposite poles of the individual magnet members 450 and 450'. Thus it will be appreciated that in the embodiments of both FIG. 6 and FIG. 7, a movement of the developer material supported on applicator member 420 in the circumferential direction is produced as applicator member 420 is rotated relative to the magnet members 450 or 450'. In addition, a movement of the developer material supported on applicator member 420 is produced in the axial direction of applicator member 420 as applicator member 420 is rotated relative to the individual magnet members 450 or 450. This arrangement therefore produces a continuous agitation of the developer material supported on applicator member 420 throughout the development cycle which maintains a more uniform concentration of toner powder across the development zone. Because of the increased uniformity of developer material which contacts the surface of copy sheet I05 having the latent electrostatic images thereon, development of the latent electrostatic images is substantially enhanced.

From the foregoing arrangement, it may thus be seen that there is provided an improved developing apparatus which yields copies of exceptionally high resolution and uniformity from electrographically formed latent electrostatic images. This result is achieved by continuous agitation and intermixing of the developer material throughout the developer cycle. To further enhance development of the latent electrostatic images on copy sheets 105, an electrical bias may be provided on platen member 550 of a suitable polarity to further enhance development of the latent electrostatic images as is well known in the art.

While the invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the true spirit and scope of the invention.

What is claimed is:

1. Apparatus for developing electrostatically charged latent images of information on a support member comprising,

a housing member adapted for storing a quantity of magnetically attractable developer material comprising magnetic carrier particles and triboelectrically charged toner particles,

a generally cylindrical applicator member rotatably journaled in said housing member for transporting a quantity of developer material from said housing member into transfer relation with a support member having latent electrostatic images thereon,

means for rotating said applicator member about the axis thereof,

magnetic means within said applicator member for attracting developer material from said housing member onto said applicator member, said magnetic means generating magnetic lines of force extending in both the axial and circumferential directions relative to said applicator member, and

means for supporting and advancing a support member hav ing electrostatically charged latent images thereon over said applicator member and said developer material sup ported thereon in the axial direction relative to the rotation of said applicator member.

2. Apparatus for developing electrostatically charged latent images of information on a support member comprising,

a housing member having a sump therein adapted for storing a quantity of magnetically attractable developer material, generally cylindrical applicator member rotatably journaled in said housing member for transporting a quantity of developer material from said housing member into transfer relation with a support member having latent electrostatic images thereon, magnetic means supported inwardly of said applicator member for attracting developer material from said housing member onto said applicator member, said magnetic means generating magnetic lines of force extending in both the axial and circumferencial directions relative to said applicator member,

means for advancing a support member having electrostatically charged latent images thereon in the axial direction over said applicator member, and

means for rotating said applicator member relative to said support member and said magnetic means to transport developer material over the surface of said support member, the relative movement between said applicator member and said magnetic means producing axial and circumferential movement of the developer material on said applicator member.

3. Apparatus according to claim 2 further including.

means for rotating said magnetic means about the axis of said cylindrical applicator member.

4. Apparatus according to claim 2 further including,

a conveyor comprising an endless belt member supported upon a plurality of roller members and adapted for movement along a path to receive developer material discharged from said cylindrical applicator member and to transport said developer material to said housing sump,

container means in communication with said endless belt member having an opening therein adjacent said endless belt member for dispensing toner powder from said container means onto said endless belt member, and

means for varying the size ofsaid opening to selectively control the quantity of toner powder dispensed and transported to said housing sump.

5. Apparatus for developing electrostatically charged latent images of information on a support member comprising,

a housing member having a sump therein adapted for storing a quantity of magnetically attractable developer material comprising magnetic carrier particles and triboelectrically charged toner particles,

a generally cylindrical applicator member rotatably journaled in said housing member for transporting a quantity of developer material from said housing member into transfer relation with a support member having latent electrostatic images thereon,

magnetic means supported inwardly of said applicator member for attracting developer material from said housing member onto said applicator member, said magnetic means generating magnetic lines of force extending in both the axial and circumferential directions relative to said applicator member,

means for advancing a support member having electrostatically charged latent images thereon in the axial direction over said applicator member, and

means for rotating said applicator member relative to said support member and said magnetic means to transport developer material from said housing sump and over the surface of said support member, the relative movement between said applicator member and said magnetic means producing a movement of the developer material on said applicator member in both the axial and circumferential directions to intermix said toner particles with said magnetic carrier particles,

a conveyor comprising an endless belt member supported about a plurality of roller members and adapted for movement along a path to receive developer material discharged from said cylindrical applicator member and to transport said developer material to said housing sump,

means for removing developer material from said cylindri cal applicator member and for discharging said developer material to said endless belt member,

container means in communication with said endless belt member for holding a quantity of toner powder therein, said container means having an opening therein adjacent said endless belt member to permit toner powder to be dispensed from said container means to said housing sump, means for advancing said endless belt member about said roller members to transport developer material discharged from said cylindrical applicator member and toner powder dispensed from said container means to said housing sump, and

means for varying the relative positioning between said container means and said endless belt member to regulate the quantity of toner powder passing through said container opening to said housing sump.

6. Apparatus according to Claim 5 further including,

means for rotating said magnetic means about the axis of said cylindrical applicator memberv i i l i It 

1. Apparatus for developing electrostatically charged latent images of information on a support member comprising, a housing member adapted for storing a quantity of magnetically attractable developer material comprising magnetic carrier particles and triboelectrically charged toner particles, a generally cylindrical applicator member rotatably journaled in said housing member for transporting a quantity of developer material from said housing member into transfer relation with a support member having latent electrostatic images thereon, means for rotating said applicator member about the axis thereof, magnetic means within said applicator member for attracting developer material from said housing member onto said applicator member, said magnetic means generating magnetic lines of force extending in both the axial and circumferential directions relative to said applicator member, and means for supporting and advancing a support member having electrostatically charged latent images thereon over said applicator member and said developer material supported thereon in the axial direction relative to the rotation of said applicator member.
 2. Apparatus for developing electrostatically charged latent images of information on a support member comprising, a housing member having a sump therein adapted for storing a quantity of magnetically attractable developer mAterial, a generally cylindrical applicator member rotatably journaled in said housing member for transporting a quantity of developer material from said housing member into transfer relation with a support member having latent electrostatic images thereon, magnetic means supported inwardly of said applicator member for attracting developer material from said housing member onto said applicator member, said magnetic means generating magnetic lines of force extending in both the axial and circumferencial directions relative to said applicator member, means for advancing a support member having electrostatically charged latent images thereon in the axial direction over said applicator member, and means for rotating said applicator member relative to said support member and said magnetic means to transport developer material over the surface of said support member, the relative movement between said applicator member and said magnetic means producing axial and circumferential movement of the developer material on said applicator member.
 3. Apparatus according to claim 2 further including, means for rotating said magnetic means about the axis of said cylindrical applicator member.
 4. Apparatus according to claim 2 further including, a conveyor comprising an endless belt member supported upon a plurality of roller members and adapted for movement along a path to receive developer material discharged from said cylindrical applicator member and to transport said developer material to said housing sump, container means in communication with said endless belt member having an opening therein adjacent said endless belt member for dispensing toner powder from said container means onto said endless belt member, and means for varying the size of said opening to selectively control the quantity of toner powder dispensed and transported to said housing sump.
 5. Apparatus for developing electrostatically charged latent images of information on a support member comprising, a housing member having a sump therein adapted for storing a quantity of magnetically attractable developer material comprising magnetic carrier particles and triboelectrically charged toner particles, a generally cylindrical applicator member rotatably journaled in said housing member for transporting a quantity of developer material from said housing member into transfer relation with a support member having latent electrostatic images thereon, magnetic means supported inwardly of said applicator member for attracting developer material from said housing member onto said applicator member, said magnetic means generating magnetic lines of force extending in both the axial and circumferential directions relative to said applicator member, means for advancing a support member having electrostatically charged latent images thereon in the axial direction over said applicator member, and means for rotating said applicator member relative to said support member and said magnetic means to transport developer material from said housing sump and over the surface of said support member, the relative movement between said applicator member and said magnetic means producing a movement of the developer material on said applicator member in both the axial and circumferential directions to intermix said toner particles with said magnetic carrier particles, a conveyor comprising an endless belt member supported about a plurality of roller members and adapted for movement along a path to receive developer material discharged from said cylindrical applicator member and to transport said developer material to said housing sump, means for removing developer material from said cylindrical applicator member and for discharging said developer material to said endless belt member, container means in communication with said endless belt member for holding a quantity of toner powder therein, said container means having an opening therein adjacent said endless Belt member to permit toner powder to be dispensed from said container means to said housing sump, means for advancing said endless belt member about said roller members to transport developer material discharged from said cylindrical applicator member and toner powder dispensed from said container means to said housing sump, and means for varying the relative positioning between said container means and said endless belt member to regulate the quantity of toner powder passing through said container opening to said housing sump.
 6. Apparatus according to Claim 5 further including, means for rotating said magnetic means about the axis of said cylindrical applicator member. 